PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       wcsnrtombs,   wcsrtombs   —   convert  a  wide-character  string  to  a  character  string
       (restartable)

SYNOPSIS

       #include <wchar.h>

       size_t wcsnrtombs(char *restrict dst, const wchar_t **restrict src,
           size_t nwc, size_t len, mbstate_t *restrict ps);
       size_t wcsrtombs(char *restrict dst, const wchar_t **restrict src,
           size_t len, mbstate_t *restrict ps);

DESCRIPTION

       For wcsrtombs(): The functionality described on this reference page is  aligned  with  the
       ISO C  standard.  Any  conflict  between  the  requirements  described  here and the ISO C
       standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard.

       The wcsrtombs() function shall convert a  sequence  of  wide  characters  from  the  array
       indirectly pointed to by src into a sequence of corresponding characters, beginning in the
       conversion state described by the object pointed to by ps.  If dst is not a null  pointer,
       the  converted  characters  shall  then  be  stored  into  the  array  pointed  to by dst.
       Conversion continues up to and including a terminating null wide  character,  which  shall
       also be stored. Conversion shall stop earlier in the following cases:

        *  When a code is reached that does not correspond to a valid character

        *  When  the next character would exceed the limit of len total bytes to be stored in the
           array pointed to by dst (and dst is not a null pointer)

       Each conversion shall take place as if by a call to the wcrtomb() function.

       If dst is not a null pointer, the pointer object pointed  to  by  src  shall  be  assigned
       either  a  null  pointer  (if  conversion  stopped due to reaching a terminating null wide
       character) or the address just past  the  last  wide  character  converted  (if  any).  If
       conversion  stopped due to reaching a terminating null wide character, the resulting state
       described shall be the initial conversion state.

       If ps is a null pointer, the wcsrtombs() function shall use  its  own  internal  mbstate_t
       object,  which  is  initialized  at  program  start-up  to  the  initial conversion state.
       Otherwise, the mbstate_t object pointed to by ps shall be used to completely describe  the
       current conversion state of the associated character sequence.

       The  wcsnrtombs()  and wcsrtombs() functions need not be thread-safe if called with a NULL
       ps argument.

       The wcsnrtombs() function shall be equivalent to the wcsrtombs() function, except that the
       conversion is limited to the first nwc wide characters.

       The wcsrtombs() function shall not change the setting of errno if successful.

       The  behavior of these functions shall be affected by the LC_CTYPE category of the current
       locale.

       The implementation shall behave as if no function defined in System Interfaces  volume  of
       POSIX.1‐2017 calls these functions.

RETURN VALUE

       If  conversion  stops  because  a  code  is  reached  that  does not correspond to a valid
       character, an encoding error occurs. In this case, these functions shall store  the  value
       of  the  macro [EILSEQ] in errno and return (size_t)-1; the conversion state is undefined.
       Otherwise, these functions shall return the number of bytes  in  the  resulting  character
       sequence, not including the terminating null (if any).

ERRORS

       These functions shall fail if:

       EILSEQ A wide-character code does not correspond to a valid character.

       These functions may fail if:

       EINVAL ps points to an object that contains an invalid conversion state.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mbsinit(), wcrtomb()

       The Base Definitions volume of POSIX.1‐2017, <wchar.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .